The present invention relates generally to the treatment of a photosensitive material such as, for example, a continuous strip of photographic film, paper or plate and, more particularly, to a processing apparatus for the photosensitive material of a type including, for example, a developing bath, a fixing bath and a washing or rinsing bath through which the photosensitive material is continuously passed for the photographic treatment thereof.
When it comes to the processing of a photographic material, for example, a continuous strip of photographic film, it is a general practice that the temperature of each of the processing solutions used in the processing apparatus is controlled to a respective predetermined temperature at all times during the processing of the photographic film. By way of example, in the case of the developing and fixing solutions, the temperature to which each of them is controlled is relatively high, for example, 30 to 40.degree. C.
On the other hand, the prior art processing apparatus particularly suited for the treatment of the photographic film is known as comprising a developing bath, a fixing bath, a rinsing bath and a drying unit all arranged in a series-connected fashion within a single housing structure which has a top covering closing the top of the assembly of developing, fixing and rinsing baths to keep their respective interiors dark. The housing structure has an inlet adjacent the developing bath and an outlet adjacent the drying unit, and the continuous strip of already exposed photographic film is continuously passed through the processing apparatus from the inlet towards the outlet, with portions of the film successively immersed in the developing, fixing and rinsing baths while sequentially travelling therethrough. The apparatus has a cross-over area between neighbouring baths, which cross-over area is generally defined by the top of a partition wall separating one processing bath from the next adjacent processing bath.
In the prior art processing apparatus, and in view of the processing solutions being relatively high in temperature as hereinbefore described, it is not unusual that vapor generated from the processing solutions is suspended in a space between the top covering and each processing bath, which vapor is subsequently transformed by condensation into liquid droplets in-contact with the top covering. Those droplets when having grown big fall by gravity into the processing baths and, also, onto the cross-over areas.
Since the vapor and, hence, the droplets generally contain constituents of the respective processing solutions contained in the developing and fixing baths, a problem arises when the droplets containing constituents of the fixing solution fall by gravity into the developing bath to mix with the developing solution, while the entry of the droplets into the fixing bath to mix with the fixing solution in a similar manner may not be considered so much a problem as the entry of the droplets into the developing bath.
As is well known to those skilled in the art of photography, the developing and fixing solutions are highly alkaline and acidic, respectively, and so are the droplets containing the constituents of the developing and fixing solutions, respectively. The entry of the acidic droplets into the developing bath results in the accelerated aging or `fatigue` of the developing solution by a phenomenon well known to those skilled in the art.
Moreover, when some droplets tending to fall by gravity onto the cross-over areas fall onto portions of the film being processed which are travelling over such cross-over areas from one processing bath to the next adjacent processing bath, the processed, or developed, film has some frames blotched with marks of the droplets. This is particularly true where the droplets fall onto that portion of the film which travels over the cross-over area between the developing and fixing baths, and should therefore be avoided for the film to be processed, i.e., developed, with no developing fault.
In an attempt to minimize the above discussed problems, the inner surface of the top covering which confronts the baths therebelow is coated with a layer of heat insulating material of an open-celled structure, one of the opppsite surfaces of the heat insulating layer remote from the top covering being formed with minute indentations, such as disclosed in, for example, the Japanese Utility Model Publication No. 59-26356 published in 1984.
However, it has been found that the prior art processing apparatus disclosed in the above mentioned Japanese publication still has a shortcoming in that the condensation of the vapor suspended in the space between the baths and the top covering cannot be completely avoided consequently particularly when the operation of the processing apparatus is interrupted for an unreasonably long time and/or when the difference is great between the ambient temperature and the temperature inside the processing apparatus as a whole, liquid droplets are formed by condensation of the vapor of the developing and fixing solutions. Thus, even the prior art processing apparatus disclosed in the above mentioned Japanese publication has such problems.
The above mentioned Japanese publication also discloses the use of a ventilating system having a ventilating duct disposed so as to extend outwardly from the top covering, which system is operated during the operation of the processing apparatus and also for a predetermined time after the processing apparatus has been interrupted or brought to a halt, for exhausting the vapor suspended inside the processing apparatus. Although the use of the ventilating system is effective to minimize the possibility of condensation of the vapor inside the processing apparatus, it causes the processing apparatus as a whole to be bulky and complicated in structure. In view of this, the processing apparatus according to the above mentioned Japanese publication is not suited for the manufacture to a table-top model.
The inventors of the present invention have devised, as disclosed in Japanese Utility Model Application No. 59-126804 (corresponding to the copending U.S. patent application Ser. No. 730,800, filed May 6, 1985, now abandoned), a processing apparatus for photosensitive material wherein droplet guide members are disposed above the processing baths so as to extend downwardly at a predetermined angle of inclination towards such respective positions, for example, centers of the surface levels of the processing solutions, where no practical problems occurs even if the droplets resulting from the condensation of the vapor fall into the processing baths.
Although this prior processing apparatus disclosed and claimed in the copending U.S. application is effective to substantially eliminate the previously discussed problems, it is believed to have room for further improvement. More specifically, where the angle of inclination of the droplet guide members can not be made sufficiently great because of the limited availability of a space above the processing baths, some of the droplets tend to remain sticking to undersurfaces of the droplet guide members and some of them tend to move towards the lower ends of the droplet guide members while travelling in a zig-zag fashion, and it often occurs that some of the droplets may fall by gravity from the undersurfaces of the droplet guide members before they reach the lower ends thereof.